%q2
A=imread('ckt-noise.jpg');
f=rgb2gray(A);
imshow(f);
R=roipoly(f);
figure,imshow(R,[]);
F= im2double(f) .* im2double(R);
figure,imshow(F,[]);
figure,imhist(F);
%gaussian noise
% the parameters - mean m and variance v.
% m=0.6235
% v= 0.00000007478
